The invention relates to a by-pass valve which is provided in the suction tube of an externally ignited internal combustion engine that is adapted to control the quantity of mixture fed to said engine during the warm running and idle running stages thereof.
In order to surmount the increased frictional moments present in a mixture compressing and externally ignited internal combustion engine which is not warm, there is required that a greater fuel-air quantity must be supplied as a function of the temperature and time during the idle operation of the engine than is necessary for an engine that has become warm. Heretofore it has been customary, for example, to open the throttle baffle plate or a by-pass as a function of temperature more than is required for an engine that has become operationally warm so that a greater mixture quantity can be aspirated by the internal combustion engine. However, the known devices have the disadvantage that both during the idle running, as well as during the warm running, the mixture is channelled near the wall of the suction tube, which results in a bad preconditioning of the mixture and a bad distribution of the mixture to the individual cylinders of the combustion engine.